The present invention relates to a new and distinct variety of Buddleja (butterfly bush) grown as an ornamental shrub for home and commercial landscapes. Butterfly bush is typically grown for its attractive, fragrant flowers that are borne throughout the growing season.
The new and distinct variety of butterfly bush resulted from a formal breeding program established by the inventor in Raleigh, N.C., United States. One of the objectives of the breeding program was to develop a very dwarf, spreading Buddleja with purple-violet flowers. ‘Blue Chip Jr’ was selected at a research station in Jackson Springs, N.C. in 2009 from a population of about 100 seedling progeny derived from a hand pollinated cross of ‘Blue Chip’ (tested as NC2004-9)×NC2006-18 (advanced test selection) made in summer 2008 in Raleigh, N.C. ‘Blue Chip’ was the female (seed) parent, and NC2006-18 was the male (pollen) parent in the aforementioned hybridization. ‘Blue Chip’ is a complex hybrid containing 3 different species and one botanical variety of Buddleja (B. davidii, B. davidii var. nanhoensis, B. lindleyana, and B. globosa). NC2006-18, the other parent of ‘Blue Chip Jr’, is a hybrid of NC2003-13×‘Miss Molly’. ‘Miss Molly’ was derived from hybridization of ‘Miss Ruby’×‘Attraction’. NC2003-13 is a hybrid of NC2001-3×‘Ellen's Blue’. ‘Miss Ruby’ was derived from hybridization of ‘White Ball’×‘Attraction’. NC2001-3 was derived from open pollination of NC2000-1. ‘White Ball’ is a complex hybrid, presumably containing B. davidii and B. fallowiana. ‘Attraction’ was derived as an open-pollinated seedling of ‘Honeycomb’, which is a hybrid of B. globosa×B. davidii. NC2000-1 is a hybrid of ‘Nanho Purple’×Buddleja lindleyana. ‘Nanho Purple’ is a variety derived from Buddleja davidii var. nanhoensis. All of the hybridizations described above, with the exception of the development of ‘White Ball’ and ‘Attraction’, were accomplished in the inventor's research program. The complete pedigree of ‘Blue Chip Jr’ is shown in FIG. 4. Of all the parents used in the development of ‘Blue Chip Jr’, the varieties ‘Blue Chip’ (U.S. Plant Pat. No. 19,991), ‘Miss Molly’ (U.S. Plant Pat. No. 23,425), ‘Miss Ruby’ (U.S. Plant Pat. No. 19,950), ‘Attraction’ (not patented), ‘White Ball’ (not patented), ‘Ellen's Blue’ (not patented), ‘Nanho Purple’ (not patented), and ‘Honeycomb’ (not patented), and the species Buddleja lindleyana are available in commerce.
The seeds resulting from the 2008 controlled hybridization process were harvested in fall of 2008 and germinated in a greenhouse in Raleigh, N.C. in the winter of 2009. The resulting 100 seedlings (approximate) were planted in field trials in spring of 2009 at a research station in Jackson Springs, N.C. These plants flowered in summer 2009, and one plant, designated NC2009-3, was selected on Aug. 14, 2009 for its very dwarf plant size, spreading habit, attractive purple-violet (RHS N82A) colored flowers, obovate leaves, flowers lacking anthers (male sterile), and lack of seed set (female sterile). This original plant demonstrated characteristics identical to those subsequently expressed on other plants when propagated from stem cuttings. This single plant is the subject of the present invention Buddleja ‘Blue Chip Jr’.
The inventor conducted the first asexual propagation of ‘Blue Chip Jr’ in fall 2009 in Raleigh, N.C., and ‘Blue Chip Jr’ has subsequently been propagated in the same location in years 2010 through 2013. In all cases, the original plant selection was propagated asexually by softwood to semi-hardwood stem cuttings. Such cuttings root readily under mist in about 14 to 21 days, and resume normal growth. Six plants derived from stem cuttings of the variety were established in experimental greenhouse trials in Raleigh, N.C. in fall, 2009 and in 2010. Subsequently, ten plants derived from stem cuttings were established in a field trial in Jackson Springs, N.C. in 2013. Through successive asexual propagations, the characteristics of the original plant have been maintained. Thus, plants derived from stem cuttings exhibit characteristics identical to those of the original plant, and no aberrant phenotypes have appeared.
Test plantings and performance evaluation over five years at a research station in Jackson Springs, N.C. and a greenhouse in Raleigh, N.C. demonstrate this variety to be relatively consistent in its characteristics even under the different growing conditions associated with yearly climatic variation.
Plants of the new variety are very dwarf after establishment in the field, being less vigorous and more dwarf than most cultivars of butterfly bush in commerce. Young plants have averaged about 45 cm of height growth per year. Plants are spreading in growth habit. Flowering occurs in the first year of growth on newly formed wood. The inflorescence is a panicle, and shows a purple-violet flower (RHS N82A) color. Flowering usually begins in late May to early June in Jackson Springs, N.C., and continues throughout the growing season until the first freeze event in October or November. An individual inflorescence flowers for about 7-10 days, depending on temperature, but new flowers are made during the entire growing season. Flowers are essentially female sterile, and the new cultivar has set no seed to date in greenhouse or field trials, even under conditions of intentional controlled pollination, an asset in landscape plantings.
The distinguishing traits of ‘Blue Chip Jr’ are very dwarf plant size, dense spreading growth habit, green obovate leaves (RHS 137C), attractive purple-violet flower color, lack of anthers (male sterility), and female structures that are essentially sterile. “Essentially sterile” is used because applicant does not preclude the possibility that seed set may be observed on rare occasions. The cultural requirements for ‘Blue Chip Jr’ are well-drained soil, full to part-sun exposure, and moderate moisture. ‘Blue Chip Jr’ exhibits no serious pest or disease problems known to the inventors, except for occasional spider mite infestation during periods of hot, dry weather.